I have been printing with a J-Head MK IV-B from Makerfarm using the latest duct printed from Nophead files.
I was having very strange issues so thought to get an alternative hot end. I ordered an official J-Head from hotends.com. J-Head MkV-BV.
The specs do not look different in the wiki .. but the Hotends.com J-Head does not protrude below the fan duct. I have not taken it out to measure, but obviously it is shorter. I could print a new extruder body and groove mount it .. but I like it recessed into the extruder body.
So really two points to this post:
1. Be aware of the length of the hot end when choosing mounting style.
2. More importantly for me .. any suggestions on an alternative fan duct or fan mount?